Children will have to pay up 17% more for their school dinners this year compared with 2010, a survey has found.

Consumer watchdog Which? also said the quality of school meals needed to improve to encourage more children to eat them and further keep costs down after finding that the price will be rising in two-thirds of schools across the country in the coming term.

There are concerns that progress made in improving children's access to healthier meals could now stall.

Average rises are about 2.5% but some local authorities have increased prices by much more. Poole council is now charging an average of £2.50, the most expensive in the country.

Doncaster council has increased prices by 17% to £1.70-£2 a meal while Lewisham council's rise is 14% to £1.40 -£1.60. The local authority with the biggest increase was Bolton at 25%, although its prices remain the lowest in the country at just £1.25.

It is estimated that in order to keep costs down, 55% of students would need to take school meals. However, the research found that just 45% of school pupils in England currently take them.

In some areas, including Wokingham district council and West Sussex county council, it is as low as 25%.

Richard Lloyd, executive director of Which?, said: "At a time when many people tell Which? their number one concern is rising food prices, it will come as an unwelcome surprise to hard-pressed families to see that some local authorities are increasing their prices by as much as 17% – well above inflation.

"School meals in most areas are still a relatively low cost and low-hassle way to provide a decent lunch for your children.

"But if schools cannot find ways to protect the extra funding that has gone to school meals and increase the number of children taking them up, there's a real risk of even more price hikes or a drop in standards, undoing the progress that has been made over the past five years."